Limiting mechanism for lifting and lowering blind

ABSTRACT

The present invention relates to a limiting mechanism for lifting and lowering a blind. The limiting mechanism includes a carrier; a resilient unit movably disposed at an end of the carrier; a recoiling roller movably disposed in the carrier and positioned proximate to the resilient unit; and a tractional unit movably disposed in the carrier and driven by the recoiling roller. The limiting mechanism is integrated into a blind body when in use, so as for a shade to be lifted or lowered when an external force is exerted thereon by a user, wherein the lifting or lowering of the shade is effectuated by the resilient unit, the recoiling roller, and the tractional unit in conjunction with the external force exerted by the user, so as to dispense with a tractional cord and enhance ease of use and use safety.

FIELD OF THE INVENTION

The present invention relates to limiting mechanisms for lifting and lowering a blind, and more particularly, to a limiting mechanism integrated into a blind body when in use, so as for a shade to be lifted or lowered when an external force is exerted thereon by a user, wherein the lifting or lowering of the shade is effectuated by a resilient unit, a recoiling roller, and a tractional unit in conjunction with the external force exerted by the user, so as to dispense with a tractional cord and enhance ease of use and use safety.

BACKGROUND OF THE INVENTION

A conventional blind (such as a Roman blind) comprises an upper beam, an elevating unit, and a shade coupled to the bottom of the upper beam. The elevating unit has a plurality of tractional cords and lifting cords. The shade comprises a plurality of slats. At least a plurality of holes are formed in each of the slats. The holes are lined up and penetrated by the lifting cords in a manner that the lifting cords are fixed to the lowest ones of the holes, respectively. To lift or lower the shade, a user pulls the tractional cords to thereby lift or lower the shade with the lifting cords.

The conventional blind has a drawback. The tractional cords are always found on one side of the shade. Toddlers are likely to put the tractional cords on their necks out of curiosity or during an inadvertent act committed in play. With a tractional cord on the neck, a toddler may end up in strangulation. Hence, tractional cords of the conventional blind pose a serious threat to child safety.

Accordingly, it is imperative to provide a limiting mechanism for lifting and lowering a blind that works without any tractional cord and features ease of use and enhanced user safety.

SUMMARY OF THE INVENTION

In view of the aforesaid drawback of the conventional limiting mechanism for lifting and lowering a blind, the inventor of the present invention believes that the conventional blind has room for improvement. Thus, the inventor of the present invention endeavors to improve the conventional blind from the inventor's experience of the related industry. Eventually, the inventor puts forth a limiting mechanism for lifting and lowering a blind that works without any tractional cord and features ease of use and enhanced user safety.

It is a primary objective of the present invention to provide a limiting mechanism for lifting and lower a blind. The limiting mechanism is integrated into a blind body when in use, so as for a shade to be lifted or lowered when an external force is exerted thereon by a user, wherein the lifting or lowering of the shade is effectuated by a resilient unit, a recoiling roller, and a tractional unit in conjunction with the external force exerted by the user, so as to dispense with a tractional cord and enhance ease of use and use safety.

In order to achieve the above and other objectives, the present invention provides a limiting mechanism for lifting and lowering a blind. The limiting mechanism includes: a carrier; a resilient unit movably disposed at an end of the carrier; a recoiling roller movably disposed in the carrier and positioned proximate to the resilient unit; and a tractional unit movably disposed in the carrier and driven by the recoiling roller.

In an embodiment of the present invention, the carrier is a frame.

In an embodiment of the present invention, the resilient unit further comprises a reel and a plurality of constant force springs. The reel has at least two spooling portions. The constant force springs is disposed on the spooling portions, respectively. The constant force springs each have an end coupled to a corresponding one of the spooling portions and another end coupled to the recoiling roller.

In an embodiment of the present invention, a first gear member is disposed on one side of the recoiling roller and configured to drive the tractional unit.

In an embodiment of the present invention, the tractional unit further comprises a cord roller, a second gear member, and a plurality of cords. The second gear member is disposed on one side of the cord roller and configured to drive the recoiling roller. The cords are windingly coupled to the cord roller.

In an embodiment of the present invention, a plurality of cord grooves are provided on the cord roller and configured to receive the cords, respectively.

The present invention provides a limiting mechanism for lifting and lowering a blind. The limiting mechanism is integrated into a blind body when in use, so as for a shade to be lifted or lowered when an external force is exerted thereon by a user, wherein the lifting or lowering of the shade is effectuated by a resilient unit, a recoiling roller, and a tractional unit in conjunction with the external force exerted by the user, so as to dispense with a tractional cord and enhance ease of use and use safety.

BRIEF DESCRIPTION OF THE DRAWINGS

To enable persons skilled in the art to gain insight into the objectives, features and advantages of the present invention, the present invention is hereunder illustrated with specific embodiments in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of the present invention;

FIG. 2 is an exploded view of the present invention;

FIG. 3 is a schematic view of the working principle of the present invention; and

FIG. 4 is another schematic view of the working principle of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 and FIG. 2, there are shown a perspective view and an exploded view of the present invention, respectively. As shown in the drawings, a limiting mechanism for lifting and lowering a blind comprises a carrier 1, a resilient unit 2, a recoiling roller 3, and a tractional unit 4.

The carrier 1 is a frame.

The resilient unit 2 is movably disposed at one end of the carrier 1. The resilient unit 2 comprises a reel 21 and a plurality of constant force springs 22. The reel 21 has at least two spooling portions 211. The constant force springs 22 are disposed on the spooling portions 211, respectively. Each of the constant force springs 22 has one end coupled to the corresponding one of the spooling portions 211.

The recoiling roller 3 is movably disposed in the carrier 1 and positioned proximate to the resilient unit 2. A first gear member 31 is disposed on one side of the recoiling roller 3. Each of the constant force springs 22 has the other end coupled to the recoiling roller 3.

The tractional unit 4 is movably disposed in the carrier 1 and driven by the recoiling roller 3. The tractional unit 4 comprises a cord roller 41, a second gear member 42, and a plurality of cords 43. The second gear member 42 is disposed on one side of the cord roller 41 and configured to mesh and drive the first gear member 31 of the recoiling roller 3. The cords 43 are windingly coupled to the cord roller 41. Also, a plurality of cord grooves 411 are provided on the cord roller 41 and configured to receive the cords 43, respectively.

Referring to FIG. 3 and FIG. 4, there are shown schematic views of the working principle of the present invention. As shown in the drawings (in conjunction with FIG. 1 and FIG. 2), to install the limiting mechanism of the present invention, a user has to put the carrier 1 in a frame 51 of a blind body 5 in a manner that the cords 43 of the tractional unit 4 are windingly disposed on braking rollers 52 disposed in the frame 51 before being connected to a shade 53. Then, the user has to fix the frame 51 of the blind body 5 to the top of a window frame. Upon completion of the installation of the limiting mechanism of the present invention, the user may give a downward pull to the shade 53 as needed; in so doing, as a result of the downward movement of the shade 53, the cords 43 of the tractional unit 4 are unwound from the cord roller 41 to thereby rotate the cord roller 41; meanwhile, the second gear member 42 disposed on one side of the cord roller 41 drives the first gear member 31 of the recoiling roller 3 and thereby rotates the recoiling roller 3. Due to the rotation of the recoiling roller 3, the constant force springs 22 are unwound from the reel 21. Furthermore, the cords 43 being unwound from the cord roller 41 rotate the braking rollers 52 to thereby rotate and drive a one-way spring 54 disposed inside each of the braking rollers 52. The one-way spring 54 is capable of generating a larger drag than the constant force springs 22 of the resilient unit 2 is, and thus the one-way spring 54 prevents the braking rollers 52 from rotating backward. Upon removal of an external force which is otherwise exerted on the shade 53, the one-way spring 54 enables the shade 53 to come to a halt and be fixed to its last position.

The lifting of the shade 53 takes place as a result of the steps of: exerting by the user an upward force on the shade 53 to remove the restriction otherwise imposed by the one-way spring 54; generating by the constant force springs 22 a larger drag than the one-way spring 54 does; winding the constant force springs 22 on the reel 21; and winding the cords 43 on the cord roller 41. Hence, the limiting mechanism of the present invention dispenses with a conventional tractional cord exposed from the shade 53 and thus enhances ease of use and user safety.

Hence, the present invention meets the three requirements of patentability, namely novelty, non-obviousness, and industrial applicability. Regarding novelty and non-obviousness, the present invention discloses a limiting mechanism which is integrated into a blind body, so as for an external force to be applied to a shade to lift or lower the shade and enable the shade to operate in conjunction with a resilient unit, recoiling roller

tractional unit with a view to dispensing with a tractional cord and ensuring ease of use and enhancing user safety. Regarding industrial applicability, products derived from the present invention meet market demands fully.

The foregoing preferred embodiments are provided to illustrate and disclose the technical features of the present invention, and are not intended to be restrictive of the scope of the present invention. Hence, all equivalent modifications and replacement of the foregoing embodiments without departing from the spirit embodied in the disclosure of the present invention should fall within the scope of the present invention as set forth in the appended claims. 

What is claimed is:
 1. A limiting mechanism for lifting and lowering a blind, comprising: a carrier; a resilient unit movably disposed at an end of the carrier; a recoiling roller movably disposed in the carrier and positioned proximate to the resilient unit; and a tractional unit movably disposed in the carrier and driven by the recoiling roller.
 2. The limiting mechanism of claim 1, wherein the carrier is a frame.
 3. The limiting mechanism of claim 1, wherein the resilient unit further comprises a reel and a plurality of constant force springs, the reel having at least two spooling portions, and the constant force springs being disposed on the spooling portions, respectively, wherein the constant force springs each have an end coupled to a corresponding one of the spooling portions and another end coupled to the recoiling roller.
 4. The limiting mechanism of claim 1, wherein a first gear member is disposed on a side of the recoiling roller and configured to drive the tractional unit.
 5. The limiting mechanism of claim 1, wherein the tractional unit further comprises a cord roller, a second gear member, and a plurality of cords, the second gear member being disposed on a side of the cord roller and configured to drive the recoiling roller, and the cords being windingly coupled to the cord roller.
 6. The limiting mechanism of claim 5, wherein a plurality of cord grooves are provided on the cord roller and configured to receive the cords, respectively. 